Controller and control method for homogeneous charge compression ignition engine

Abstract

Provided are a controller and a control method for a homogeneous charge compression ignition engine, which are capable of obtaining a highly efficient and stable combustion state over a wide range of load condition. A correction factor computing section executes combustion control with an excess air ratio smaller than approximately 3 when a predetermined condition is satisfied and computes a correction factor for correcting deviations between execution values of valve-opening timings and valve-opening periods of an intake valve and an exhaust valve and basic valve-opening timings and basic valve-opening periods of the intake valve and the exhaust valve which are previously determined for each operation condition, based on a timing at which an ion current becomes maximum detected by a combustion-timing detection section, in the combustion control with the excess air ratio smaller than approximately 3.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a controller and a control method for a homogeneous charge compression ignition engine which causes an air-fuel mixture formed in a combustion chamber to self-ignite by a compression of a piston under at least a part of operation conditions.[0003]2. Description of the Related Art[0004]In a homogeneous charge compression ignition engine, an air-fuel mixture formed by the mixture of air and fuel in a combustion chamber reaches a self-ignition temperature by the compression of a piston to simultaneously start combustions at a plurality of positions in a space inside the combustion chamber. Specifically, a electric spark (electric discharge), which is used for ignition in a conventional gasoline internal combustion engine, is not required in the homogeneous charge compression ignition engine.[0005]A rise in temperature of the air-fuel mixture by the compression of the piston is brought about...

AI Technical Summary

Benefits of technology

The patent text is about controlling the timing and duration of valves in an internal combustion engine to improve combustion efficiency and stability. This is particularly useful when there is a change in fuel composition or when the engine is operating in a super-excess air state. By using a correction factor, the engine can achieve a highly efficient and stable combustion state even under challenging load conditions.

Problems solved by technology

However, if the temperature of the mixture becomes higher than needed, a combustion speed increases to cause combustion with vibrations similar to knocking.

On the other hand, if the temperature of the mixture becomes lower than needed, the ignition becomes unstable to cause an accidental fire.

However, the conventional technologies have the following problem.

Therefore, a timing at which the ion current becomes maximum cannot be detected.

Therefore, there is a problem in that the temperature of the air-fuel mixture cannot be controlled to a temperature suitable for the combustion based on the ion-current information.

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